Dual-stage multi-roll leveler and metal strip material flattening method

ABSTRACT

Dual-stage multi-roll leveler embodiments of the general inventive concept include independent sets of first stage work rolls and second stage work rolls, with each set of work rolls including one or more upper work rolls disposed above one or more lower work rolls. An adjustable but equal entry side-to-exit side gap is present between the upper and lower work rolls of each work roll set. An exemplary dual-stage leveler removes shape defects and coil set and/or curl from a moving strip material through a combination of work roll gap adjustment and first and/or second stage work roll bending. Because there is no feathering out of work roll penetration in either stage, differential roll speed and the problems associated therewith are eliminated.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 15/387,274, filed on Dec. 21, 2016, which is herebyincorporated by reference as if fully recited herein.

TECHNICAL FIELD

Embodiments of the application are directed to multi-rollshape-correction levelers and, more particularly, multi-rollshape-correction levelers designed to overcome problems associated withdifferential roll speed.

BACKGROUND

The basic concept of a multi-roll shape-correction leveler (hereinafteralso “shape-correction leveler” or just “leveler” for brevity) has beenknown for many years. Shape-correction levelers were developed toaccount for the undesirable shape defects often imparted to metal stripmaterial during the production thereof. Common but non-limiting forms ofsuch shape defects are shown in FIGS. 1A-1D, and include coil set, crossbow, edge wave, and center buckle, respectively.

As represented in FIG. 2, known shape-correction levelers typically useopposing, substantially parallel sets of multiple work rolls 5, 10 thatoften are supported by back-up rolls and associated bearings designed towithstand high separating forces and to control the bending anddeflection of the work rolls. The work rolls are normally positioned sothat an upper row of work rolls 5 are located above a cooperating lowerrow of work rolls 10. A gap 15 of adjustable dimension is normallypresent between the upper and lower work rolls 5, 10. A metal strip tobe flattened is passed through the gap 15.

During a flattening operation, metal strip material (typically from acoil) is fed into the entrance of the leveler as indicated, whereafterit is caused to pass between the opposing sets of work rolls 5, 10 (seeFIG. 2) before exiting from the exit side of the leveler. Each set ofwork rolls is placed into contact with the metal strip by driving oneset of work rolls toward the other so that a leveling (flattening) forceis impressed upon the metal strip as it passes therebetween.

In known levelers, the gap 15 between the upper work rolls 5 and lowerwork rolls 10 at the entry side of the leveler (and work rolls) isdeliberately made to be different than the gap 15 at the exit side ofthe leveler (and work rolls). More specifically, the gap 15 at the entryside of the leveler is set to be less than the gap at the exit side ofthe leveler to provide more work roll penetration, and more working ofthe metal strip, nearer the exit side of the leveler. In other words,the gap distance, and the amount of work roll penetration, feathers outfrom the entry side to the exit side of the leveler (i.e., in thedirection of material flow).

As shown in FIG. 4, contact between the upper and lower work rolls of aknown leveler and a metal strip material being flattened, causes themetal strip to be repeatedly bent up and down (i.e., to S-wrap) as itpasses through the work rolls located near the entry side of theassociated leveler. This repeated bending of the metal strip materialremoves stress-induced shape defects from the metal strip material. Ascan also be observed in FIG. 4, the amount of work roll penetration intothe metal strip material, and the degree of resulting S-wrapping,decreases as the strip material moves toward the exit side of theleveler. The feathering out of work roll penetration from the entry sideto the exit side of a leveler, allows shape defects to be removed by afirst group of work rolls located nearer the entry side of the levelerand coil set to be removed by a second group of work rolls locatednearer the exit side of the leveler. The number of work rolls involvedin each operation may vary according to the total number of work rollspresent and the degree of feathering (i.e., the difference between entryside and exit side gap) employed.

A shape-correction leveler may also be operated to selectively applyforces of different magnitudes to different areas of a strip of materialpassing therethrough. This selective application of force bends the workrolls to a shape that causes particular zones of the strip of material(from edge to edge) to be worked more than other zones as the strippasses through the leveler. Thus, shorter zones of the strip may beselectively elongated to match the length of the longer zones. Thisallows a shape-correction leveler to correct a variety of differentshape defects.

For purposes of illustration, a typical shape-correction leveler setup20 for correcting center buckle is shown in FIG. 3A, while a typicalsetup 25 for correcting edge wave is shown in FIG. 3B. The upwardlydirected arrows in FIGS. 3A-3B represent upward work roll bending forcesexerted at various locations along the length of the lower work rolls 30of the leveler as needed to correct one or more shape defects. In theknown leveler examples of FIGS. 3A-3B, the work roll bending forces areproduced by pairs of driven adjusting wedges 35. In known levelers, suchadjusting wedges operate to bend all of the lower and/or upper workrolls present. For example, in the case of the known leveler designshown in FIGS. 3A-3B, any bending forces produced by the adjustingwedges 35 would be applied to all of the lower work rolls 30.

Each work roll of a typical shape-correction leveler is normally drivento propel the strip of material through the leveler during a leveling(flattening) operation. A shape-correction leveler drive system commonlyconsists of a main motor, a reduction gearbox, and a pinion gearbox,that cooperate to provide output rotation to each work roll.

An interesting phenomenon occurs when the work rolls of knownshape-correction levelers penetrate into a strip of material beingprocessed and the material S-wraps through the work rolls. With lightpenetration (e.g., at the exit end of the leveler) the roll surfacespeed substantially matches the strip speed. However, when the rollspenetrate deeper (e.g., at the entry end of the leveler), the rollsurface speed tends to run slower than the strip speed. This phenomenonoccurs because the material has a bend radius, (entry end of leveler)and the surface speed of the material on the inside of the bend radiusis moving slower than the surface speed on the outside of the bendradius (see FIG. 4). This is analogous to the wheel speed on anautomobile, wherein the wheels on both sides of the automobile rotate atthe same RPM when the automobile is going straight, but the wheels onthe inside of the curve will rotate slower than the wheels on theoutside of the curve when the automobile is making a turn. In the caseof a shape-correction leveler, the work rolls are contacting the insidebending radius of the strip material, so the rolls on the entry end ofthe leveler run slower to match the slower inside radius surface speed.One example of this phenomenon, from an entry to an exit end of anexemplary leveler, is depicted in FIG. 5.

The aforementioned phenomenon may be referred to as differential rollspeed (DRS). When the leveler work rolls are all driven together at thesame speed (see e.g., FIG. 4 and FIG. 6), the entry rolls try to pushthe strip material through the exit rolls, while the exit rolls try tohold the material back. DRS causes several issues in a leveler. Oneissue is that when the work rolls are geared together, the DRS causeshigh loading on the entry work rolls and internal torque windup withinthe roll drive system—which may cause premature failure of the drivecomponents. Another issue is that more power tends to be consumed whenthe work rolls are fighting each other. Yet another issue is that DRStends to cause a compression of the strip material rather than astretching of the material, which reduces the effectiveness of theleveler.

Various approaches to overcoming the effects of DRS have been attempted,including but not limited to, the use of torque limiters on driveshafts; the use of torque limiting clutches on entry work roll clusters;complex and costly work roll drive systems such as systems where eachwork roll is individually driven, and systems utilizing split entry andexit work roll clusters with individual drive motors; and the use of twoseparate levelers. While torque limiters have been placed on work rolldrive shafts, it has proven difficult to produce a slip torque levelthat is high enough to actually process strip material on levelers soequipped. Torque limiters have also proven to have a short service lifeand have been unreliable. Placing a torque limiter on the entry workroll cluster of a leveler so as to control the torque to the entrycluster based on total load may be effective at reducing the internaltorque windup typically resulting from DRS, but torque windup stilloccurs within each cluster and a high torque concentration may also bepresent at the split between the entry and exit roll clusters. Drivingeach work roll of a leveler individually is very costly and can resultin control difficulties when an associated leveler is used to flattenstrip material across a range of material and shape defect conditions.The use of split entry and exit roll drive clusters with individualmotors can also be effective at reducing the internal torque windupnormally resulting from DRS, but torque windup still occurs within eachwork roll cluster and a high torque concentration may also be present atthe split between the entry and exit roll clusters.

The desirability of overcoming the negative effects of DRS should beapparent from the foregoing remarks. It should also be apparent thatimprovements over the techniques previously used to mitigate oreliminate the effects of DRS would also be desirable. Exemplaryembodiments presented herein overcome the effects of DRS using a single,dual-stage leveler, that allows for a simplified work roll drive system.

SUMMARY

Exemplary dual-stage multi-roll leveler designs presented herein differfrom known leveler designs at least because the work rolls of anexemplary dual-stage leveler are divided into two (or more) independentstages. Additionally, the entry side work roll gap and exit side workroll gap are kept equal, thereby eliminating the aforementionedfeathering out of work roll penetration common to known levelers.

In one exemplary dual-stage leveler embodiment, the leveler includes afirst, entry side leveling stage (first stage) and a separate second,exit side leveling stage (second stage) that receives the strip materialfrom the first stage. Each of the first stage and the second stageincludes a set of cooperating upper and lower work rolls. The firststage work rolls, the second stage work rolls, or both the first stageand the second stage work rolls, may be subjected to uniform rollbending. Typically, bending of the first stage work rolls is employedfor the purpose of removing shape defects from strip material throughmaterial elongation as described above, whereas bending of the secondstage work rolls is typically employed to remove coil set and/or curlfrom the strip material. The first stage work roll set and the secondstage work roll set are independent of one another and may also beseparately driven. As used herein, the terms “first,” “entry side,”“second,” and “exit side” are intended to indicate only the order inwhich the provided independent sets of work rolls will contact the stripmaterial as it passes through the leveler. No other meaning is to beimplied.

The first stage work roll set and second stage work roll set may be—butdo not have to be—mounted in a cassette that is installable within thework envelope of the leveler. When used, the cassette may be dividedinto an upper half and a lower half, with the upper half including upperwork rolls and associated supporting elements, and the lower halfincluding lower work rolls and associated supporting elements.

An exemplary dual-stage leveler may include a gap adjusting mechanism,such as entry side and exit side jack screw assemblies, for adjustingthe gap between (and the penetration of) the upper and lower work rollsof the first stage and second stage work roll sets. In at least someembodiments, the entry side and exit side jack screw assemblies aregeared together so that operation of the jack screw assemblies willalways result in a uniform entry side-to-exit side work roll gap orchange in work roll gap.

Work roll bending in an exemplary multi-stage leveler may beaccomplished by various techniques known in the art. In one exemplaryembodiment, an assembly of wedges may be used to produce a uniformbending of all of the lower, upper, or lower and upper work rolls of oneor both of the first stage and second stage work roll sets. A linearactuator or other motive device may be used to selectively displace thewedges as needed to produce the required amount of work roll bending. Inanother exemplary embodiment, When work roll bending is utilized, theamount of total work roll penetration into the strip material beingleveled may be controlled by a combination of gap adjusting mechanism(e.g., jack screw assembly) movement and wedge movement.

Other aspects and features of the inventive concept will become apparentto those skilled in the art upon review of the following detaileddescription of exemplary embodiments along with the accompanying drawingfigures.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following descriptions of the drawings and exemplary embodiments,like reference numerals across the several views refer to identical orequivalent features, and:

FIGS. 1A-1D illustrate several shape defects common to metal stripmaterial;

FIG. 2 depicts an exemplary upper and lower set of work rolls of a knownshape-correction leveler design;

FIG. 3A depicts an exemplary technique for correcting a center buckleshape defect using a known shape-correction leveler;

FIG. 3B depicts an exemplary technique for correcting an edge wave shapedefect using a known shape-correction leveler;

FIG. 4 and FIG. 5, in combination, help to illustrate the problem ofdifferential roll speed on a known multi-roll shape-correction leveler;

FIG. 6 represents a commonly used shape-correction leveler drive schemewhere all of the leveler work rolls are driven at the same speed;

FIG. 7 is a side view of one exemplary embodiment of a dual-stagemulti-roll leveler according to the general inventive concept, havingwork roll bending capability with respect to the lower work rolls of thefirst stage work roll set;

FIG. 8 is a schematic representation of the movement of a strip materialthrough the work rolls of the exemplary dual-stage multi-roll leveler ofFIG. 7;

FIG. 9 is a side view of one exemplary embodiment of a dual-stagemulti-roll leveler according to the general inventive concept, havingwork roll bending capability with respect to the lower work rolls of thesecond stage work roll set;

FIG. 10 is a side view of one exemplary embodiment of a dual-stagemulti-roll leveler according to the general inventive concept, havingwork roll bending capability with respect to the lower work rolls ofboth the first stage work roll set and the second stage work roll set;

FIG. 11 is one exemplary embodiment of a work roll-containing cassettemodule that may be utilized in an exemplary dual-stage multi-rollleveler;

FIG. 12 depicts one exemplary drive scheme for a dual-stage multi-rollleveler;

FIG. 13 depicts an alternative exemplary drive scheme for a dual-stagemulti-roll leveler; and

FIGS. 14A-14C represent the exemplary dual-stage multi-roll levelersdepicted in FIG. 7 and FIGS. 9-10, where alternative embodiments of workroll bending mechanisms have been installed thereto.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The aforementioned problem of differential roll speed on a multi-rollleveler of typical, known design, is illustrated via the combination ofFIGS. 4-6. Particularly, when the rolls of a multi-roll shape-correctionleveler are all driven together at the same speed (see FIG. 6) with afeathering out of work roll penetration (see FIG. 4), the entry rollsattempt to push the strip material being leveled through the exit rolls,while the exit rolls resist such movement.

Exemplary dual-stage multi-roll leveler (hereinafter “dual-stageleveler” for brevity) embodiments described herein are able to overcomethe aforementioned problems associated with differential roll speed in anovel and efficient manner. Schematic side views of several suchexemplary dual-stage levelers 100, 600, 700 appear in FIG. 7 and FIGS.9-10.

As shown in FIG. 7, one exemplary dual-stage leveler embodiment 100 hasan entry side 105 and an exit side 110, with material flow occurring inan entry-to-exit direction as indicated by the arrow. Typically, and aswould be familiar to one of skill in the art, strip material to beflattened is fed from a coil into the entry side 105 of the dual-stageleveler 100.

The exemplary dual-stage leveler 100 also includes a frame 115, withwhich is associated an upper and lower platen 120, 125. A workingenvelope 130 is defined between the platens 120, 125 and the entry side105 and exit side 110 of the dual-stage leveler 100.

Disposed within the working envelope 130 of the exemplary leveler 100 isa first, entry side leveling stage (first stage) 135 and a separatesecond, exit side leveling stage (second stage) 140, each of whichincludes its own set 135 a, 140 a of work rolls. As previouslyexplained, the terms “first,” “entry side,” “second,” and “exit side”are intended to indicate only the order in which the providedindependent sets of work rolls will contact the strip material as itpasses through the leveler. No other meaning is to be implied.

The first stage 135 includes a work roll set 135 a comprising aplurality of upper work rolls 145 disposed above a plurality of lowerwork rolls 155. Likewise, the second stage 140 also includes a work rollset 140 a comprising a plurality of upper work rolls 150 disposed abovea plurality of lower work rolls 160.

While the first stage work roll set 135 a is shown to have a total ofnine work rolls and the second stage work roll set 140 a is shown tohave a total of five work rolls in the exemplary dual-stage levelerembodiment 100 of FIG. 7, it is to be understood that different numbersof first stage work rolls and second stage work rolls may be utilized inother dual-stage leveler embodiments. Likewise, while the work rolls145, 155 of the first stage work roll set 135 a and the work rolls 150,160 of the second stage work roll set 140 a are shown to be the samediameter in the exemplary dual-stage leveler 100 of FIG. 7, it should beunderstood that in other dual-stage leveler embodiments the works rollsof one leveler stage and the work rolls of the other leveler stage(s)may have dissimilar diameters.

The upper work rolls 145, 150 and the lower work rolls 155, 160 of theexemplary dual-stage leveler 100 are arranged in a substantiallyparallel relationship between the entry side 105 and exit 110 side ofthe leveler, with the longitudinal axis of each work roll orientedsubstantially perpendicular to the direction of travel of the stripmaterial that will be passed through the leveler. As described in moredetail below, the upper work rolls 145 and the lower work rolls 155 ofthe first stage work roll set 135 a cooperate to remove strip materialshape defects during leveler operation, while the upper work rolls 150and the lower work rolls 160 of the second stage work roll set 145 awill cooperate primarily to remove coil set and/or induced curl from thestrip material during leveler operation.

The upper work rolls 145, 150 and/or the lower work rolls 155, 160 ofthe first and/or second stage work roll sets 135 a, 140 a may besupported by a corresponding set of backup rolls, such as the exemplarybackup rolls 165, 170 shown to support the upper work rolls 145, 150 inFIG. 7. The backup rolls are disposed in flights, such that two backuprolls support each work roll. It may also be possible to eliminate thebackup rolls in other embodiments.

The first and second leveler stages 135, 140 also include supportbearings 185 that function to support the work rolls 145, 150, 155,160—whether directly or through associated backup rolls. In theexemplary dual-stage leveler 100 of FIG. 7, the first stage work rollset includes six upper support bearings and six lower support bearings,while the second stage work roll set includes five upper supportbearings and three lower support bearings. The number of bearingspresent in a given leveler embodiment will depend on the number of workrolls and/or backup rolls present and, therefore, the number of bearingsused may be different in other leveler embodiments.

A gap adjusting mechanism is provided to adjust the space between theplatens 120, 125 of the exemplary leveler 100 and, consequently, the gapbetween the upper work rolls 145, 150 and lower work rolls, 155, 160 ofthe first stage and second stage work roll sets. The gap between theupper work rolls 145, 150 and the lower work rolls 155, 160 of the firststage and second stage work roll sets is provided to allow metal stripmaterial to pass therethrough during leveler operation.

In some embodiments, the gap adjusting mechanism of a dual-stage levelerembodiment may be configured for independent adjustment of the platenspacing along the entry and exit sides of the leveler. In otherexemplary embodiments, the gap adjusting mechanism may be configuredsuch that operation thereof will simultaneously adjust both the entryside and exit side platen spacing. In any case, the initial setting andsubsequent adjustment of the platen spacing occurs in a manner thatmaintains parallelism between the platens 120, 125 and, consequently, anequal gap between the upper and lower work rolls 145, 155 of the firststage work roll set 135 a and the upper and lower work rolls 150, 160 ofthe second stage work roll set 140 a.

In the exemplary dual-stage leveler 100 of FIG. 7, the gap adjustingmechanism is comprised of pairs of vertically oriented entry side andexit side jack screw assemblies 190, 195. The entry side and exit sidejack screw assemblies 190, 195 may be geared or otherwise connectedand/or controlled so that parallelism between the platens 120, 125 andan equal gap between the upper and lower work rolls of the first stagework roll set 135 a and second stage work roll set 140 a will bemaintained during operation of the jack screw assemblies. As would alsobe familiar to one of skill in the art, one or more electric motors (oranother type of motor) may be utilized to drive the jack screwassemblies 190, 195. It is also possible that the motor-driven jackscrew assemblies 190, 195 may be replaced with hydraulic cylinders orother suitable actuating devices in other embodiments.

As should be understood from the foregoing description, the featheringout of work roll penetration common to known multi-roll levelers iseliminated in an exemplary dual-stage leveler design. Consequently, asshown in the exemplary dual-stage leveler 100 of FIG. 7, the entry gap175 a and exit gap 175 b between the upper and lower work rolls 145, 150of the first stage work roll set 135 a will be equal, as will the entrygap 180 a and exit gap 180 b between the upper and lower work rolls 150,160 of the second stage work roll set 140 a.

As briefly mentioned above, shape defect removal is further accomplishedin the first stage of the exemplary dual-stage leveler embodiment 100 ofFIG. 7 by way of uniformly bending the first stage work rolls toselectively elongate or otherwise selectively deform at least certainsections of the strip material being flattened. Work roll bending may beperformed on the upper work rolls 145 and/or lower works rolls 155 ofthe first stage work roll set 135 a of an exemplary dual-stage leveler.In the exemplary dual-stage leveler embodiment 100 of FIG. 7, only thelower work rolls 155 of the first stage work roll set 135 a are subjectto such bending.

Work roll bending in an exemplary dual-stage leveler according to thegeneral inventive concept may be achieved by any one or more of severaltechniques. In the case of the exemplary dual-stage leveler 100embodiment of FIG. 7, work roll bending is accomplished by way of anadjusting wedge assembly 200 that lies subjacent to the lower work rolls155 of the first stage work roll set 135 a. The adjusting wedge assembly200 may be comprised of a plurality of individual adjusting wedges whosepositions may be selectively adjusted by way of corresponding actuators205 to impart the desired work roll bending. For example and withoutlimitation, the adjusting wedge assembly 200 may be configured and mayoperate as represented in FIG. 7, such that all of the lower work rolls155 of the first stage work roll set 135 a will be locally bent (i.e.,work roll penetration will be adjusted) by a like amount during movementof a given wedge.

In previous multi-roll leveler designs, the upper crown or the wedgeassembly of the leveler must tilt to provide deep entry rollpenetration—resulting in little exit roll penetration and an overallwork roll penetration profile that feathers out from the entry side tothe exit side of the leveler. Because of such work roll penetrationfeathering, this traditional leveler design and setup creates thedifferential roll speed and undesirable internal torque windup describedabove. In contrast, when an exemplary dual-stage leveler is configuredas described herein, such as in the case of any of the exemplarylevelers 100, 600, 700, there is no feathering out of work rollpenetration and no resulting differential roll speed and/or undesirableinternal torque windup as is common with known multi-roll levelers.

In the exemplary dual-stage leveler 100 of FIG. 7, uniform penetrationof the work rolls 145, 155 across the first stage work roll set may beproduced by a combination of gap adjustment using the jack screwassemblies 195, 200 and roll bending using the wedge assembly 200, whileuniform penetration of the work rolls 150, 160 across the second stagework roll set 140 a is produced exclusively through gap adjustment usingthe jack screw assemblies.

As a result of equal entry side and exit side work roll penetrationwithin each leveler stage, as described above, the rotational speed ofthe entry and exit work rolls of each leveler stage will be the same(i.e., equal to the surface speed experienced by the inside bend radiusof the strip material being processed). Differential roll speed is,therefore, eliminated by such a design, as is any associated internaltorque windup within each stage. The lack of internal torque windupallows all of the torque applied to each work roll to be utilized forworking the strip material, and the applied torque will be substantiallyequally distributed to each of the work rolls within a given stage(although the first and last work roll will may experience slightly lesstorque due to a lesser material wrap angle). Also, the lack of internaltorque windup allows for a very predictable and manageable torquedistribution.

As can be further observed in FIG. 7, and as schematically indicated inFIG. 8, proper location of the support bearings 185 in the dual-stageleveler 100 results in a space 210 between the exit side of the firststage work roll set and the entry side of the second stage work rollset. Strip material exiting the work rolls of the first work roll stagemust traverse this space 210 in order for the unrestrained leading endthereof to reach the work rolls of the second work roll stage. Asindicated in FIG. 8, the strip material 215 may also be somewhatupwardly-directed in an area 220 near the first work roll stage workroll set as a result of an up-curl imparted by the work rolls 145, 155thereof. Strip material may alternatively be somewhatdownwardly-directed upon exiting the first work roll stage work roll setdue to down-curl, in embodiments where the first work roll stage workrolls are arranged such that the most downstream work roll is an upperwork roll (e.g., if the upper and lower work roll configurations 145,155 are reversed). To help ensure proper initial engagement of themoving strip material 215 with the second stage work roll set, theexemplary dual-stage leveler 100 may include a guide 225, deflectorassembly, threading plate, or some other mechanism for ensuring that theleading end of the strip material 215 is directed into the gap betweenthe work rolls 150, 160 of the second work roll stage work roll set.

An even better understanding of the operation of the exemplarydual-stage leveler 100 of FIG. 7 may be gained by reference to FIG. 8,where it can be observed that when the strip material 215 is passedthrough the dual-stage leveler 100 in the indicated material flowdirection, the work rolls 145, 155 of the first stage work roll set 135a will engage the strip material to remove shape defects from the stripmaterial as explained above. That is, work roll penetration and bendingin the first leveler stage are controlled and directed such that thestrip material 215 is caused to wrap partially around at least some ofthe work rolls 145, 155 of the first stage work roll set 135 a so as toelongate or otherwise deform at least certain areas of the stripmaterial as necessary to remove shape defects present therein. Likewise,work roll penetration in the second leveler stage is simultaneously suchthat the work rolls 150, 160 of the second stage work roll set 140 awill engage the strip material 215 in a manner by which any remainingcoil set is removed from the strip material, as also explained above.The second work roll stage work roll set is also operative to remove anycurl (see below) or other undesirable shape characteristics imparted tothe strip material by the first stage work roll set 135 a.

Another exemplary dual-stage leveler embodiment 600 is depicted in FIG.9. The exemplary leveler 600 is similarly constructed and operates in amanner similar to the exemplary dual-stage leveler 100 shown in FIG. 7,except that in this leveler embodiment 600, work roll bending capabilityis incorporated into the second leveler stage as opposed to the firstleveler stage in the leveler 100 of FIG. 7. Consequently for purposes ofclarity, only leveler components relative to a description of thedifferences between the exemplary leveler 600 of FIG. 9 and theexemplary leveler 100 of FIG. 7 are shown in FIG. 9.

As with the exemplary dual-stage leveler 100 of FIG. 7, the exemplarydual-stage leveler embodiment 600 of FIG. 9 includes within a workingenvelope thereof a first, entry side leveling stage (first stage) 605and a separate second, exit side leveling stage (second stage) 610, eachof which includes its own set 605 a, 610 a of work rolls. The firststage work roll set 605 a comprises a plurality of upper work rolls 615disposed above a plurality of lower work rolls 620. Likewise, the secondstage work roll set 610 a comprises a plurality of upper work rolls 625disposed above a plurality of lower work rolls 630. The upper work rolls615, 625 and the lower work rolls 620, 630 of the exemplary dual-stageleveler 600 are again arranged in a substantially parallel relationshipbetween the entry side and exit side of the leveler, with thelongitudinal axis of each work roll oriented substantially perpendicularto the direction of travel of the strip material that will be passedthrough the leveler.

In the exemplary dual-stage leveler 600 of FIG. 9, shape defect removalby the first stage work roll set 605 a is accomplished exclusivelythrough work roll penetration produced by gap adjustment using a gapadjusting mechanism such as the jack screw assemblies described abovewith respect to the leveler 100 of FIG. 7. In contrast, removal of coilset and/or induced curl from the strip material by the second stage workroll set 610 a is accomplished by a combination of gap adjustment anduniform roll bending using, for example, a wedge assembly 635 like orsimilar to that described above with respect to the exemplary leveler100 of FIG. 7. Although the functionality of the first stage and secondstage of the exemplary leveler 600 is essentially reversed from that ofthe exemplary leveler 100, the penetration of the work rolls 615, 620 ofthe first stage work roll set 605 a into the strip material beingleveled and the penetration of the work rolls 625, 630 of the secondstage work roll set 610 a into the strip material being leveled is stilluniform across the respective first and second stages. Likewise, theentry gap 640 a and exit gap 640 b between the upper and lower workrolls 615, 620 of the first stage work roll set 605 a will be equal, aswill the entry gap 645 a and exit gap 645 b between the upper and lowerwork rolls 625, 630 of the second stage work roll set 610 a.Consequently, the feathering out of work roll penetration common toknown multi-roll levelers is again eliminated by the design of theexemplary dual-stage leveler 600, which eliminates any problemsassociated with differential roll speed and/or undesirable internaltorque windup as is common with known multi-roll levelers.

Yet another exemplary dual-stage leveler embodiment 700 is depicted inFIG. 10. The exemplary leveler 700 is similarly constructed and operatesin a manner similar to the exemplary dual-stage leveler 100 shown inFIG. 7, except that in this leveler embodiment 700, work roll bendingcapability is incorporated into both the first leveler stage and thesecond leveler stage, as opposed to only the first leveler stage in theleveler 100 of FIG. 7. Consequently for purposes of clarity, onlyleveler components relative to a description of the differences betweenthe exemplary leveler 700 of FIG. 10 and the exemplary leveler 100 ofFIG. 7 are shown in FIG. 10.

As with the exemplary dual-stage leveler 100 of FIG. 7, the exemplarydual-stage leveler embodiment 700 of FIG. 10 includes within a workingenvelope thereof a first, entry side leveling stage (first stage) 705and a separate second, exit side leveling stage (second stage) 710, eachof which includes its own set 705 a, 710 a of work rolls. The firststage work roll set 705 a comprises a plurality of upper work rolls 715disposed above a plurality of lower work rolls 720. Likewise, the secondstage work roll set 710 a comprises a plurality of upper work rolls 725disposed above a plurality of lower work rolls 730. The upper work rolls715, 725 and the lower work rolls 720, 730 of the exemplary dual-stageleveler 700 are again arranged in a substantially parallel relationshipbetween the entry side and exit side of the leveler, with thelongitudinal axis of each work roll oriented substantially perpendicularto the direction of travel of the strip material that will be passedthrough the leveler.

In the exemplary dual-stage leveler 700 of FIG. 10, shape defect removalby the first stage work roll set 705 a may be accomplished by work rollpenetration produced by gap adjustment using a gap adjusting mechanism(such as the jack screw assemblies described above with respect to theleveler 100 of FIG. 7), by uniform roll bending using, for example, awedge assembly 735 a like or similar to that described above withrespect to the exemplary leveler 100 of FIG. 7, or by a combination ofgap adjustment and uniform roll bending. Similarly, removal of coil setand/or induced curl from the strip material by the second stage workroll set 710 a may be accomplished by work roll penetration produced bygap adjustment using a gap adjusting mechanism (such as the jack screwassemblies described above with respect to the leveler 100 of FIG. 7),by uniform roll bending using, for example, a wedge assembly 735 a likeor similar to that described above with respect to the exemplary leveler100 of FIG. 7, or by a combination of gap adjustment and uniform rollbending.

As with the exemplary dual-stage leveler 100 of FIG. 7 and the exemplarydual-stage leveler 600 of FIG. 9, the penetration of the work rolls 715,720 of the first stage work roll set 705 a of the exemplary leveler 700of FIG. 10 into the strip material being leveled and the penetration ofthe work rolls 725, 730 of the second stage work roll set 710 a into thestrip material being leveled is again uniform across the respectivefirst and second stages. Likewise, the entry gap 740 a and exit gap 740b between the upper and lower work rolls 715, 720 of the first stagework roll set 705 a will be equal, as will the entry gap 745 a and exitgap 745 b between the upper and lower work rolls 725, 730 of the secondstage work roll set 710 a. Consequently, the feathering out of work rollpenetration common to known multi-roll levelers is again eliminated bythe design of the exemplary dual-stage leveler 700, which eliminates anyproblems associated with differential roll speed and/or undesirableinternal torque windup as is common with known multi-roll levelers.

Each of the exemplary dual-stage levelers 600, 700 shown in FIGS. 9-10may incorporate previously described features of the exemplarydual-stage leveler 100 of FIG. 7. For example and without limitation,the levelers 600, 700 may utilize a leveler frame and platens, a gapadjustment mechanism, a roll bending wedge assembly or assemblies, backup rolls, support bearings and/or a material guide that is similar to orthe same as that described above with respect to the exemplarydual-stage leveler 100 of FIG. 7. Similarly, the exemplary dual-stagelevelers 600, 700 shown in FIGS. 9-10 may include a number of worksrolls and/or a work roll diameter that is different from that shown,whether in the first stage, the second stage, or both stages thereof.

In some exemplary dual-stage leveler embodiments, such as the dual-stageleveler 100 shown in FIG. 7, the work rolls and position controlhardware (e.g., wedges, actuators) may be built into the leveler. Forexample, the work rolls may be mounted in roll frames that are securedto the leveler platens in a manner that does not provide for easyremoval, and the wedge actuators may be mounted to the leveler frame,etc., and may be mechanically coupled to the corresponding wedges forpushing or pulling movement thereof.

Alternatively, the work rolls of a dual-stage leveler embodiment may beprovided as part of a removable cassette assembly. One such exemplarycassette assembly 300 is represented in FIG. 11. As shown, the exemplarycassette assembly 300 is divided into a removable upper and lowercassette subassembly 305, 310.

The upper cassette subassembly 305 includes an upper sub-platen 315 thatis adapted for releasable affixation to the upper platen of anassociated dual-stage leveler (e.g., to the upper leveler platen 120 inFIG. 7). An upper cassette work roll retention frame 320 is locatedsubjacent to the upper sub-platen 315 and is adapted to retain upperwork rolls 325, 330 of respective first stage and second stage work rollsets. The upper cassette work roll retention frame 320 may be furtheradapted for retention of first stage and second stage upper backup rolls335, 340, bearings, and/or a variety of other work roll-relatedcomponents.

In a similar manner to the upper cassette subassembly 305, the lowercassette subassembly 310 includes a lower sub-platen 355 that is adaptedfor releasable affixation to the lower platen of an associateddual-stage leveler (e.g., to the lower leveler platen 125 in FIG. 7). Alower cassette work roll retention frame 360 is located superjacent tothe lower sub-platen 355 and is adapted to retain lower work rolls 345,350 of respective first stage and second stage work roll sets. The lowercassette work roll retention frame 320 may be further adapted forretention of first stage and second stage lower backup rolls 365, 370,bearings, and/or a variety of other work roll-related components.

In the same manner as described with respect to the exemplary dual-stageleveler 100 of FIG. 7, the upper work rolls 325 and the lower work rolls345 define a first stage work roll set and the upper work rolls 330 andthe lower work rolls 350 define an independent second stage work rollset of the exemplary cassette assembly 300. The exemplary cassetteassembly may include any of the other features associated with the firstand second stage of the exemplary dual-stage leveler 100 of FIG. 7. Forexample, and without limitation, the cassette assembly 300 may includean infeed director 375, and a guide 380, deflector assembly, threadingplate, or some other means for ensuring that the leading end of thestrip material fed into the cassette assembly is directed into the gapbetween the work rolls 330, 350 of the second work roll stage work rollset.

The exemplary cassette assembly 300 may further include a wedge assembly385 that, in this embodiment, is a part of the lower cassettesubassembly 310. The wedge assembly 385 may include a plurality ofindividual and selectively movable wedges as previously described inregard to the aforementioned wedge assembly 200 of FIG. 7. In the caseof this exemplary cassette assembly 300, however, a first set ofactuators 390 is provided for moving the wedges in apenetration-increasing direction, and a second set of actuators 395 isprovided for moving the wedges in a penetration-decreasing direction.

The dual-actuator design of this exemplary cassette embodiment allowsthe first set of actuators 390 to remain mechanically disconnected fromthe associated wedges, which facilitates installation and removal of thecassette assembly 300 to/from a dual-stage leveler. To furtherfacilitate installation and removal of the cassette assembly in such anembodiment, the actuator stroke of the first set of actuators 390 mayalso be longer than the maximum wedge travel distance so as to allow fora gap between the pistons of the actuators 390 and a contacting surfaceof the wedges when the actuator pistons are withdrawn. The first set ofactuators 390 may be mounted, for example, to a frame portion of anassociated dual-stage leveler or to another structure in sufficientlyclose proximity thereto.

The second set of actuators 395 may be mounted to the lower cassettesubassembly 310. As the actuators of the first set of actuators 390 arenot mechanically connected to the wedges of the wedge assembly 385 inthis exemplary cassette assembly 300, said actuators do not function toretract the wedges subsequent to making a penetration-increasingmovement thereof. Instead, the second set of actuators 395 is utilizedto move the wedges in a penetration-decreasing direction. The actuatorsof the second set of actuators 395 may or may not be mechanicallyconnected to the wedges of the wedge assembly 385.

The cassette assembly 300 is mounted within a dual-stage leveler withthe upper sub-platen 315 of the upper cassette subassembly 305releasably affixed to the upper platen of the leveler, and the lowersub-platen 355 of the lower cassette subassembly 310 releasably affixedto the lower platen of the leveler. With the cassette assembly soinstalled to the remainder of a dual-stage leveler, flattening of metalstrip material may proceed as described above with respect to FIG. 7 andFIG. 8.

In one exemplary technique for removal of the cassette assembly 300, theupper cassette subassembly 305 is first brought substantially intocontact with the lower cassette subassembly 310. Thereafter, bothsubassembly platens 315, 355 may be detached from the leveler platensand the entire cassette assembly 300 may be rolled or otherwise removedfrom the associated leveler, such as by means of a moveable cart, etc.

A roll drive system is used to drive the work rolls of a dual-stageleveler, such as but not limited to, the exemplary dual-stage levelershown in FIG. 7 and/or FIGS. 9-10. One such exemplary drive system 400is schematically depicted in FIG. 12. In this exemplary drive system400, a first motor 405 is provided to drive the work rolls 410 of afirst work roll set corresponding to a first stage 415 of an associateddual-stage leveler. Similarly, a second motor 420 is provided to drivethe work rolls 425 of a second work roll set corresponding to a secondstage 430 of the dual-stage leveler. The motors 405, 420 may be variablespeed drive motors. In the exemplary drive system 400 of FIG. 10, thefirst motor 405 associated with the first leveler stage 415 acts as themaster drive for the leveler. The second motor 420 (and second stagework rolls 425) may be operated at a different rotational speed than thefirst motor. For example, the second motor may be operated at arotational speed that is slightly greater than the rotational speed ofthe first motor 405 (and first stage work rolls 410)—depending on thestrip material being processed and first stage work roll penetration—toensure that the second stage work roll set does not impede the forwardmotion of the strip material after it leaves the first stage work rollset.

As would be understood by one of skill in the art, the motors 405, 420may be coupled to respective gearboxes, such as the multi-output piniongearboxes 435, 440 shown. Output torque from the gearboxes 435, 440 maybe transferred to the work rolls 410, 425 of the respective work rollsets by way of corresponding sets of couplings 445, 450. In thisexemplary embodiment, the couplings 445, 450 are flexible in nature toaccommodate adjustments in work roll penetration and bending.

Another exemplary roll drive system 500 is schematically depicted inFIG. 13. In this exemplary drive system 500, a single motor 505 isprovided to drive the work rolls 510 of a first work roll setcorresponding to a first stage 515 of an associated dual-stage leveler,as well as the work rolls 520 of a second work roll set corresponding toa second stage 525 of the dual-stage leveler. The motor 505 may again bea variable speed drive motor.

The motor 505 is coupled to respective first stage and second stagegearboxes, such as the multi-output pinion gearboxes 530, 535 shown. Inthis exemplary drive embodiment, coupling of the motor 505 to thegearboxes 530, 535 is accomplished by way of a belt drive assembly 540that includes a drive belt 545, first belt pulley 550 coupled to themotor output, and a second belt pulley 555 coupled to the input of thesecond stage gearbox 535.

It may again be desirable to operate the second stage work rolls 520 ata rotational speed that is slightly greater than the rotational speed ofthe first stage work rolls 510 (as explained above). Consequently, thefirst belt pulley 550 and the second belt pulley 555 of the belt driveassembly 540 may have dissimilar diameters to provide for such adifference in work roll rotational speed.

As in the roll drive system 400 of FIG. 12, output torque from thegearboxes 530, 535 of this exemplary roll drive system 500 may betransferred to the work rolls 510, 520 of the respective work roll setsby way of corresponding sets of couplings 560, 565. In this exemplaryembodiment, the couplings 560, 565 are again flexible in nature toaccommodate adjustments in work roll penetration and bending. Atorque-limiting clutch 570 or other suitable protective element may alsobe provided to limit the amount of torque applied to the second stagework roll set.

It is to be understood that the roll drive systems 400, 500 of FIGS.12-13, respectively, have been shown and described herein only forpurposes of illustration. Other roll drive designs may also be used inother exemplary dual-stage leveler embodiments. For example, and withoutlimitation, any of the various roll drive systems shown in FIGS. 7-11 ofU.S. patent application Ser. No. 15/076,503 filed on Mar. 21, 2016, maybe used to drive the work rolls of an exemplary dual-stage leveler.

While uniform bending of work rolls is described as being performable bya wedge assembly with respect to the exemplary dual-stage levelers 100,600 of FIGS. 7 and 9 and by a pair of wedge assemblies with respect tothe exemplary dual-stage leveler 700 of FIG. 10, it is also possible toproduce uniform roll bending with other designs. One non-limitingexample of an alternative uniform roll bending design is depicted inFIGS. 14A-14C, which correspond respectively with the exemplarydual-stage leveler designs shown in FIG. 7 and FIGS. 9-10. Moreparticularly, FIG. 14A shows the exemplary leveler 100 of FIG. 7equipped with an alternative work roll bending mechanism; FIG. 14B showsthe exemplary leveler 600 of FIG. 9 equipped with an alternative workroll bending mechanism; and FIG. 14C shows the exemplary leveler 700 ofFIG. 10 equipped with an alternative work roll bending mechanism.

In FIG. 14A, reference numbers indicating the same elements as in FIG. 7have been retained, while new reference numbers are provided for thealternative work roll bending mechanism and components thereof. Certainnon-relevant reference numbers have also been omitted from FIG. 14A forthe purpose of clarity.

As shown, the exemplary dual-stage leveler 100 is constructed andoperates as described above with respect to FIG. 7, except that thewedge assembly 200 provided for uniformly bending the lower work rolls155 of the first stage work roll set 135 a has been replaced with a workroll bending mechanism 800 comprising a plurality of work roll bendingcylinders 805. The work roll bending cylinders 805 are verticallyoriented such that the piston rods 810 thereof (or elements affixedthereto) will exert an indirect bending force on the lower work rolls155 when the piston rods are caused to be extended from the cylinders.

As would be understood by one of skill in the art, the quantity andarrangement of the work roll bending cylinders 805 may vary based on thespecific design of the first stage work roll set 135 a. In any case, thework roll bending mechanism 800 and its plurality of work roll bendingcylinders 805 will cause a uniform bending of the lower work rolls 155of the first stage work roll set 135 a.

In FIG. 14B, reference numbers indicating the same elements as in FIG. 9have been retained, while new reference numbers are provided for thealternative work roll bending mechanism and components thereof. Certainnon-relevant reference numbers have also been omitted from FIG. 14B forthe purpose of clarity.

As shown, the exemplary dual-stage leveler 600 is constructed andoperates as described above with respect to FIG. 9, except that thewedge assembly 635 provided for uniformly bending the lower work rolls630 of the second stage work roll set 610 a has been replaced with awork roll bending mechanism 825 comprising a plurality of work rollbending cylinders 830. The work roll bending cylinders 830 arevertically oriented such that the piston rods 835 thereof (or elementsaffixed thereto) will exert an indirect bending force on the lower workrolls 630 when the piston rods are caused to be extended from thecylinders.

As would be understood by one of skill in the art, the quantity andarrangement of the work roll bending cylinders 830 may vary based on thespecific design of the second stage work roll set 610 a. In any case,the work roll bending mechanism 825 and its plurality of work rollbending cylinders 830 will cause a uniform bending of the lower workrolls 630 of the second stage work roll set 610 a.

In FIG. 14C, reference numbers indicating the same elements as in FIG.10 have been retained, while new reference numbers are provided for thealternative work roll bending mechanism and components thereof. Certainnon-relevant reference numbers have also been omitted from FIG. 14C forthe purpose of clarity.

As shown, the exemplary dual-stage leveler 800 is constructed andoperates as described above with respect to FIG. 10, except that thewedge assembly 735 a provided for uniformly bending the lower work rolls720 of the first stage work roll set 705 a has been replaced with a workroll bending mechanism 850 comprising a plurality of work roll bendingcylinders 855 and the wedge assembly 735 b provided for uniformlybending the lower work rolls 730 of the second stage work roll set 710 ahas been replaced with a work roll bending mechanism 875 comprising aplurality of work roll bending cylinders 880. The work roll bendingcylinders 855 of the first stage work roll bending mechanism 850 arevertically oriented such that the piston rods 860 thereof (or elementsaffixed thereto) will exert an indirect bending force on the first stagelower work rolls 720 when the piston rods are caused to be extended fromthe cylinders. Similarly, the work roll bending cylinders 880 of thesecond stage work roll bending mechanism 875 are vertically orientedsuch that the piston rods 885 thereof (or elements affixed thereto) willexert an indirect bending force on the second stage lower work rolls 730when the piston rods are caused to be extended from the cylinders.

As would be understood by one of skill in the art, the quantity andarrangement of the first stage work roll bending cylinders 855 may varybased on the specific design of the first stage work roll set 705 a.Likewise, the quantity and arrangement of the second stage work rollbending cylinders 880 may vary based on the specific design of thesecond stage work roll set 710 a In any case, the work roll bendingmechanisms 825, 850 and the plurality of work roll bending cylinders855, 800 associated therewith will cause a uniform bending of the lowerwork rolls 720, 730 of the respective first stage and second stage workroll sets 705 a, 710 a.

Dual-stage leveler embodiments, such as those described and shownherein, overcome the problems of differential roll speed and resultinginternal torque windup that are inherent to known multi-roll levelerdesigns. Such dual-stage leveler embodiments may also produce otherbenefits. For example, because all of the work rolls in a given stage ofan exemplary dual-stage leveler may be subjected to equal penetrationand bending, a larger differential (bending/flattening) path can beachieved with fewer work rolls. Thus, it may be possible to achieve adifferential path through a dual-stage leveler with fewer work rollsthan would be required to achieve a comparable differential path througha traditional multi-roll leveler. Further, since the problems associatedwith differential roll speed are eliminated by an exemplary dual-stageleveler, it may be possible to plunge (penetrate) the work rolls of agiven leveler stage deeper into the strip material being processed,which should correspondingly produce a greater percent yield of thematerial with less torque required from the work roll drive system.

While certain embodiments of the invention are described in detailabove, the scope of the invention is not considered limited by suchdisclosure, and modifications are possible without departing from thespirit of the invention as evidenced by the following claims:

What is claimed is:
 1. A dual-stage multi-roll leveler for flattening amoving strip material, comprising: a framework defining a work envelopehaving a material entry side and a material exit side; a first levelingstage including a driven first stage work roll set located within thework envelope to receive the strip material through an entry sidethereof, the first stage work roll set including a plurality of upperwork rolls disposed above a plurality of lower work rolls with a uniformentry side and exit side gap therebetween; a second leveling stageincluding a driven second stage work roll set disposed within the workenvelope and located downstream of the first stage work roll set so asto receive the strip material therefrom, the second stage work roll setbeing independent from the first stage work roll set and including aplurality of upper work rolls disposed above a plurality of lower workrolls with a uniform entry side and exit side gap therebetween; a gapadjusting mechanism configured to uniformly adjust the gap between theupper and lower work rolls of the first stage and second stage work rollsets; and a work roll bending mechanism configured to uniformly bend theupper work rolls or the lower work rolls of the second stage work rollset; wherein a lack of feathering out of work roll penetrationeliminates any possible torque windup due to differential roll speed. 2.The leveler of claim 1, wherein the first stage work roll set isoperative to remove shape defects from the strip material, and thesecond stage work roll set is operative to remove coil set from thestrip material.
 3. The leveler of claim 1, wherein the gap adjustingmechanism comprises a plurality of powered jack screw assemblies.
 4. Theleveler of claim 3, wherein the plurality of powered jack screwassemblies are coupled together for concurrent and equivalent movement.5. The leveler of claim 1, wherein the second stage work roll bendingmechanism is selected from the group consisting of an adjustable wedgeassembly and a plurality of vertically-oriented cylinders.
 6. Theleveler of claim 5, wherein the adjustable wedge assembly includes: aplurality of individually displaceable wedges, the wedges configured toact on each upper work roll or each lower work roll to the same degree;and a plurality of actuators for selectively and controllably displacingthe wedges.
 7. The leveler of claim 1, further comprising a materialguide disposed between the first stage work roll set and the secondstage work roll set, the material guide adapted to direct strip materialexiting the first stage work roll set into the second stage work rollset.
 8. The leveler of claim 1, further comprising a drive system forrotationally driving the upper work rolls and/or the lower work rolls ofthe first stage work roll set and the second stage work roll set.
 9. Theleveler of claim 8, wherein the drive system includes a first drivemotor that is coupled to driven work rolls of the first stage work rollset, and a second drive motor that is coupled to the driven work rollsof the second stage work roll set.
 10. The leveler of claim 8, whereinthe drive system includes a single drive motor that is coupled to boththe driven work rolls of the first stage work roll set and the drivenwork rolls of the second stage work roll set, in a manner that allowsthe driven work rolls of each stage to be driven at different rotationalspeeds.
 11. The leveler of claim 10, wherein the drive system includes adrive belt assembly that employs a drive belt rotating first stage andsecond stage pulleys of dissimilar diameter, such that the driven workrolls of the second stage work roll set will rotate at a greatervelocity than the driven work rolls of the first stage work roll set.12. A dual-stage multi-roll leveler for flattening a moving stripmaterial, comprising: a framework defining a work envelope having amaterial entry side and a material exit side; a first leveling stageincluding a driven first stage work roll set located within the workenvelope to receive the strip material through an entry side thereof,the first stage work roll set including a plurality of upper work rollsdisposed above a plurality of lower work rolls with a uniform entry sideand exit side gap therebetween; a second leveling stage including adriven second stage work roll set disposed within the work envelope andlocated downstream of the first stage work roll set so as to receive thestrip material therefrom, the second stage work roll set beingindependent from the first stage work roll set and including a pluralityof upper work rolls disposed above a plurality of lower work rolls witha uniform entry side and exit side gap therebetween; a gap adjustingmechanism configured to uniformly adjust the gap between the upper andlower work rolls of the first stage and second stage work roll sets; awork roll bending mechanism configured to uniformly bend the upper workrolls or the lower work rolls of the first stage work roll set; and awork roll bending mechanism configured to uniformly bend the upper workrolls or the lower work rolls of the second stage work roll set; whereina lack of feathering out of work roll penetration eliminates anypossible torque windup due to differential roll speed.
 13. The levelerof claim 12, wherein the first stage work roll set is operative toremove shape defects from the strip material, and the second stage workroll set is operative to remove coil set from the strip material. 14.The leveler of claim 12, wherein the gap adjusting mechanism comprises aplurality of powered jack screw assemblies.
 15. The leveler of claim 14,wherein the plurality of powered jack screw assemblies are coupledtogether for concurrent and equivalent movement.
 16. The leveler ofclaim 12, wherein the first stage and second stage work roll bendingmechanisms are selected from the group consisting of an adjustable wedgeassembly and a plurality of vertically-oriented cylinders.
 17. Theleveler of claim 16, wherein the adjustable wedge assembly includes: aplurality of individually displaceable wedges, the wedges configured toact on each upper work roll or each lower work roll to the same degree;and a plurality of actuators for selectively and controllably displacingthe wedges.
 18. The leveler of claim 12, further comprising a materialguide disposed between the first stage work roll set and the secondstage work roll set, the material guide adapted to direct strip materialexiting the first stage work roll set into the second stage work rollset.
 19. The leveler of claim 12, further comprising a drive system forrotationally driving the upper work rolls and/or the lower work rolls ofthe first stage work roll set and the second stage work roll set. 20.The leveler of claim 19, wherein the drive system includes a first drivemotor that is coupled to driven work rolls of the first stage work rollset, and a second drive motor that is coupled to the driven work rollsof the second stage work roll set.
 21. The leveler of claim 19, whereinthe drive system includes a single drive motor that is coupled to boththe driven work rolls of the first stage work roll set and the drivenwork rolls of the second stage work roll set, in a manner that allowsthe driven work rolls of each stage to be driven at different rotationalspeeds.
 22. The leveler of claim 21, wherein the drive system includes adrive belt assembly that employs a drive belt rotating first stage andsecond stage pulleys of dissimilar diameter, such that the driven workrolls of the second stage work roll set will rotate at a greatervelocity than the driven work rolls of the first stage work roll set.23. The leveler of claim 12, wherein the first stage work roll bendingmechanism is selectively operable and the second stage work roll bendingmechanism is selectively operable, such that the leveler is operablewith first stage work roll bending, second stage work roll bending, or acombination of first stage and second stage work roll bending.
 24. Amethod for flattening a moving strip material, comprising: providing afirst leveling stage including a driven first stage work roll set toreceive the strip material through an entry side thereof, the firststage work roll set including a plurality of upper work rolls disposedabove a plurality of lower work rolls with a uniform entry side and exitside gap therebetween; providing a second leveling stage including adriven second stage work roll set disposed within the work envelope andlocated downstream of the first stage work roll set so as to receive thestrip material therefrom, the second stage work roll set beingindependent from the first stage work roll set and including a pluralityof upper work rolls disposed above a plurality of lower work rolls witha uniform entry side and exit side gap therebetween; providing a gapadjusting mechanism configured to uniformly adjust the gap between theupper and lower work rolls of the first stage and second stage work rollsets; associating a work roll bending mechanism with the upper workrolls or the lower work rolls of the first stage work roll set;associating a work roll bending mechanism with the upper work rolls orthe lower work rolls of the second stage work roll set; using the gapadjusting mechanism as needed to set a uniform gap between the upper andlower work rolls of the first stage and second stage work roll sets;selectively operating the work roll bending mechanism associated withthe first stage work roll set to produce work roll bending within thefirst leveling stage when desired; and selectively operating the workroll bending mechanism associated with the second stage work roll set toproduce work roll bending within the second leveling stage when desired;wherein flattening of the strip material is facilitated by work rollbending in one or both of the first leveling stage and the secondleveling stage; and wherein a lack of feathering out of work rollpenetration eliminates any possible torque windup due to differentialroll speed.